KR0166597B1 - Flame retardant composition - Google Patents

Abstract

A composition comprising: (a) polyethylene having a density equal to or less than 0.925 gram per cubic centimeter, grafted with an unsaturated aliphatic diacid anhydride; and (b) magnesium hydroxide, surface treated with a saturated or unsaturated carboxylic acid or a metal salt thereof in an amount of about 0.1 to about 1 part by weight of acid or salt per 100 parts by weight of magnesium hydroxide.

Description

[Name of invention]

Flameproof Composition

Detailed description of the invention

[Field of Invention]

The present invention relates to a flame retardant composition comprising an ethylene copolymer and a magnesium hydroxide filler. The composition is useful for the insulation and coating of communication media such as electrical conductors and fiber optic cables.

[Background of invention]

Regardless of the purpose of the transmission or communication of power, wires and cables are usually stored in open or unheated areas before construction. If the insulation or sheath becomes stiff and cracks at low temperatures, the integrity of the wire or cable is broken and short circuits and the resulting problems can actually occur. Thus, specifications for layers for insulation and covering generally require that these materials pass the curing test at low temperatures. Often, as is desired by wire and cable manufacturers, low temperature capacity below minus 50 ° C. or higher, especially for hypotheses, for example in Canada and the like, is mentioned.

Typical power cables consist of conductors of metal coated with a polymer material. These elements are usually twisted to form a core and protected with other polymer sheets or coating materials. In certain cases, extra protection is provided by inserting a wrap between the core and the sheet.

Salt resistant compositions comprising polyethylene and magnesium hydroxide are useful for wire and cable applications, where polyethylene gives flexibility and magnesium hydroxide gives salt resistance. Unfortunately, these compositions do not meet the most desirable low temperature capabilities as far as curability is concerned. For example, it is difficult to achieve low-temperature curing at 0 ° C. as a linear low density polyethylene salt composition.

[Description of Specific Example of the Invention]

It is therefore an object of the present invention to provide excellent low temperature hardening resistance, and thus to provide a salt composition which is useful even in the coldest climate. Other objects and advantages will be apparent later.

According to the present invention the object is (a) polyethylene grafted with unsaturated aliphatic diacid anhydrides having a density of equal to or less than 0925 g / cm 3; And (b) magnesium hydroxide surface-treated with a saturated or unsaturated carboxylic acid or metal salt thereof in an amount of approximately 0.1 to 1 parts by weight per 100 parts by weight of magnesium hydroxide.

[Description of Preferred Embodiment (s)]

Polyethylene having a density of equal to or less than 0.925 g / cm 3 is a co-polymer of ethylene with at least one alpha-olefin having 3 to 12 carbon atoms, preferably 3 to 8 carbon atoms. The density of the copolymer is preferably equal to or less than 0.915 g / cm 3, preferably at least 0.860 g / cm 3. For example, it may include (1) a catalyst comprising chromium and titanium, (2) a catalyst comprising magnesium, titanium, halogens and electron donors or (3) vanadium, electron donors, alkylaluminum halide modifiers. (alkyl aluminum halide modifier) and halocarbon promoter can be prepared in the presence of a catalyst. Catalysts and processes for the preparation of such co-polymers are described in US Pat. Nos. 4,101,445 and 4,302,565 and European Patent Application No. 0 120 501 published October 3,1984.

The melt index of the polyethylene may be in the range of about 0.1 to 10 g per 10 minutes, preferably in the range of about 0.4 to 10 g per 10 minutes. The melt index was determined by measuring at 190 ° C. according to ASTM D-1238 (American Society for Testing Materials) condition E. Suitable alpha-olefin comonomers include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. The fraction of polyethylene that contributes to comonomer (s) other than ethylene is in the range of approximately 1 to 49 weight percent based on the weight of the copolymer, preferably approximately 15 to 40 weight percent.

Anhydrides of unsaturated aliphatic diacids are usually grafted with various polyolefins. These anhydrides may have 4 to 20 carbon atoms, preferably 4 to 10 carbon atoms. Examples of anhydrides useful in the present invention include maleic anhydride, itaconic anhydride and nadic anhydride. Preferred anhydrides are maleic anhydride. If present after grafting, excess anhydride can be evaporated off at a temperature within the range of approximately 200-250 ° C.

Grafting can be accomplished by organic lump oxide catalysts such as dicumyl peroxide, lauroyl peroxide, benzoyl peroxide, tertiary butyl perbenzoate and di ( t-butyl) peroxide (di (tertiary-butyl) peroxide), cumene hydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 (2,5 -dimethyl-2,5di (t-butylperoxy) hexyne-3), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (2,5-dimethyl-2,5-di (t- butylperoxy) hexane, t-butyl hydroperoxide, isopropyl percarbonate and alpha, alpha'-bis (t-butylperoxy) diisopropylbenzene (alpha, alpha'- It may be performed using a free radical generator such as bis (t-butylperoxy) diisopropylbenzene). The organic peroxide catalyst can be added together with the anhydride.

The grafting temperature may be in the range of about 100 to 300 ° C, and preferably in the range of about 150 to 200 ° C.

Typical procedures for the grafting of maleic anhydride on polyethylene are described in US Pat. No. 4,506,056.

Grafting can also be carried out by adding a solution of anhydride, an organic peroxide catalyst and an organic solvent to the polyethylene in the granulated form. The organic peroxide catalyst is soluble in an organic solvent. Various organic solvents that are inert to the reaction can be used. Examples of useful organic solvents are acetone, methyl ethyl ketone, methyl propyl ketone, 3-pentanone and other ketones. Other carrier solvents may be used that allow for the dissolution of peroxides and anhydrides and are capable of being well separated off under appropriate evaporation conditions. Acetone is a preferred solvent because it acts as a stripping agent for residues such as non-grafted anhydrides or anhydride by-products and the like.

The anhydride solution may comprise approximately 10 to 50 weight percent anhydride, approximately 0.05 to 5 weight percent organic peroxide catalyst and approximately 50 to 90 weight percent organic solvent based on the total weight of the solution. Preferred solutions include approximately 20 to 40 weight percent anhydride, approximately 0.1 to 2 weight percent organic peroxide catalyst and approximately 60 to 80 weight percent organic solvent.

The anhydride grafted polyethylene comprises about 0.05 to 5 parts by weight of anhydride per 100 parts by weight of polyethylene, preferably about 0.1 to 2 parts by weight per 100 parts by weight of polyethylene.

The polyethylene may also be grafted with unsaturated monomeric silanes having one or more hydrolysable functional groups in order to produce hydrolysable polyethylene and thus enable moisture curing. Although such grafting can be carried out simultaneously with the grafting of the unsaturated aliphatic diacid anhydride, the grafting can also be carried out before or after the grafting of the anhydride if necessary.

The silane grafted copolymer can be prepared by the method described below. In this co-polymer, the fraction contributing to the silane is present in the co-polymer in an amount of about 0.5 to 10% by weight based on the weight of the polymer, preferably in an amount of about 0.5 to 4% by weight. . Generally speaking, any unsaturated monomer silane comprising at least one hydrolysable functional group can be used. The silanes used to modify the copolymer are, among others, vinyl trimethoxy silane, vinyl triethoxy silane or vinyl isopropoxy silane. Alkenyl alkoxy silanes such as vinyl trialkoxy silane, and the like. If you need moderate hydraulic stability or better self stability, vinyl triisobutoxy silane or vinyl tris (2-ethyl-hexoxy) silane may be used. Can be used.

Hydrolyzable silanes and anhydride grafted polyethylenes include dibuthl tin dilaurate, dioctyl tin maleate, stannous octate, and lead naphthenate Conventional silanes such as zinc octate, iron 2-ethyl hexoate and other metal carboxylates can be crosslinked with water in the presence of a condensation catalyst. Crosslinking by addition of a cocatalyst such as tetramethoxy titanate, tetraisopropyl titanate, tetramethyl titanate or other organic titanates, as mentioned in US Pat. No. 4,446,279. Can be further promoted. The catalysts may be introduced into the composition in conventional amounts, typically from about 0.005 to 1 part by weight of the primary catalyst and about 0.25 to 10 parts by weight of the cocatalyst per 100 parts by weight of the co-polymer.

A typical method for preparing silane grafted polyethylene is as follows:

100 parts of ethylene / 1-butene co-polymer with a density of 0.90, 0.2 parts of polymerized 1,3-dihydro-2,2,4-trimethyl-quinoline (antioxidant), 0.1 part of dicumyl peroxide and vinyl tri- Four parts of 2-ethyl-hexoxy silane are mixed in a Brabender mixer at a temperature within the range of approximately 80-115 ° C. which is the temperature at which dicumyl peroxide can be maintained below the decomposition temperature. After mixing for 5 minutes, the temperature is raised to a temperature within the range of approximately 150 to 220 ° C. The batch is then mixed for 5 to 10 minutes during which grafting of the silane to the copolymer occurs. The antioxidant is used to capture radicals to control the amount of crosslinking. For example, 3 parts of vinyl triisobutyoxysilane, 0.1 part of antioxidant, tetrakis (methylene (3-5-di-t-butyl-4-hydroxyhydro-cinnamate)) methane (tetrakis (methylene) (3-5-di-tert-butyl-4-hydroxyhydro-cinnamate)) methane, initial mixing is within the range of 110 to 120 ° C., grafting is repeated for 5 minutes at 185 ° C. do.

Suitable for use in preparing silane grafted polyethylene and these polymers, various unsaturated silanes having hydrolyzable functional groups such as alkoxy, oxyaryl, oxyaliphatic and halogen, etc. 4,412,042, 4,413,066, 4,574,133 and 4,593,071.

It should be noted that the same organic peroxide catalyst can be used for silane grafting as in anhydride grafting.

The magnesium hydroxide is one of those commonly used in wire and cable applications. Preferred magnesium hydroxide is characterized by the following characteristics: strain of 3.0 10-3 or less in (a) (101) direction, crystal size of 800 angstroms or more in (b) (101) direction and (c) BET method. It has a determined surface area of 20 m ² / g or less.

Preferred magnesium hydroxide and its preparation are described in US Pat. No. 4,098,762. Preferred properties of the magnesium hydroxide are those having a surface area of 10 m ² / g or less, as determined by the BET method.

The amount of magnesium hydroxide used in the composition may be within the range of about 100 to 180 parts by weight magnesium hydroxide per 100 parts by weight of anhydride grafted polyethylene, preferably about 120 to 160 parts by weight per 100 parts by weight of anhydride grafted polyethylene. It may be within the range of negative magnesium hydroxide.

The magnesium hydroxide is surface treated with saturated or unsaturated carboxylic acids or metal salts thereof having approximately 8 to 24 carbon atoms, preferably having 12 to 18 carbon atoms. Mixtures of these acids and / or salts may also be used if desired. Examples of suitable carboxylic acids are oleic acid, stearic acid, palmitic acid, isostearic acid and lauric acid, and the metals that can be used in the form of salts of these acids are zinc, aluminum, calcium, magnesium and barium, and Their salts are magnesium stearate, zinc oleate, calcium palmitate, magnesium oleate and aluminum stearate. The amount of acid or salt may be within the range of about 0.1 to 1 part by weight of acid or salt per 100 parts by weight of magnesium hydroxide, and preferably within the range of about 0.15 to 0.50 part by weight of acid or salt per 100 parts by weight of magnesium hydroxide.

Various conventional additives may be added in the compositions of the present invention in conventional amounts. Typical additives include homeostatic agents, UV absorbers, antistatic agents, pigments, dyes, other fillers including carbon black and aluminum silicates, lubricants, flame retardants, stabilizers, crosslinking agents, halogenation agents, smoke inhibitors, crosslinking accelerators, carboxylic acids Processing aids such as metal salts, lubricants, plasticizers and viscosity modifiers.

The electrical conductor may comprise a transmission medium of metal such as copper or carbon and the like, or glass or plastic filaments for example used in optical fiber applications.

Patents and other publications mentioned herein are incorporated herein by reference.

The invention is embodied by the following embodiments.

[Examples 1 to 12]

Polyethylene 1 is an unmodified low density polyethylene that is a co-polymer of ethylene and 1-hexene with a density of 0.917 g / cm 3 and a melt index of 3.4 g per 10 minutes.

Polyethylene 2 is a co-polymer grafted with ethylene and 1-butene maleic acid having a density of 0.900 g / cm 3 and a melt index of 0.4 g per 10 minutes. The polyethylene was grafted with 0.3 parts by weight of maleic anhydride per 100 parts by weight of polyethylene according to the above-mentioned method.

All magnesium hydroxides used in these embodiments fall within the preferred definitions of magnesium hydroxide mentioned above and are identical except for their surface treatment.

Magnesium hydroxide 1 is surface treated with 3 parts by weight of stearic acid per 100 parts by weight of magnesium hydroxide.

Magnesium hydroxide 2 is surface treated with 3 parts by weight of oleic acid per 100 parts by weight of magnesium hydroxide. The magnesium hydroxide is granular.

Magnesium hydroxide is surface treated with 0.25 parts by weight of oleic acid per 100 parts by weight of magnesium hydroxide. The magnesium hydroxide is granular.

The antioxidant is tetrakis (methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)) methane.

Sixteen compositions were treated with test specimens as required for low temerature brittleness (LTB), that is, the test procedure for ASTM D-746-73 and the test procedure was performed. Low temperature cure is described in degrees Celsius.

The variables and results are shown in the table.

Note to Table: Embodiment 12, wherein the resin is polyethylene2 grafted with 100% maleic acid and magnesium hydroxide is surface treated with 0.25 parts by weight of oleic acid per 100 parts by weight of magnesium hydroxide, exhibits a low temperature cure of -59.5 ° C. .

Claims (10)

(a) polyethylene grafted with unsaturated aliphatic diacid anhydride and having a density of less than or equal to 0.925 g / cm 3; And (b) magnesium hydroxide surface-treated with a saturated or unsaturated carboxylic acid or metal salt thereof in an amount of about 0.1 to 1 parts by weight per 100 parts by weight of magnesium hydroxide; Composition comprising a. The composition of claim 1 wherein said anhydride is maleic anhydride. The composition of claim 1 wherein said polyethylene is further grafted with hydrolyzable unsaturated monomer silane. The method according to claim 1, wherein the magnesium hydroxide is less than 3.0 × 10 ^-3 strain in the (a) (101) direction and (b) crystal size of 800 Angstroms or more in the (101) direction and (c) BET method Composition having a surface area of less than or equal to 20 m ² / g. The composition according to claim 4, wherein the magnesium hydroxide has a surface area characteristic of 10 m ² / g or less as determined by the BET method. The composition of claim 1, wherein the amount of magnesium hydroxide is present in an amount of approximately 100 to 180 parts by weight magnesium hydroxide per 100 parts by weight of anhydride grafted polyethylene. The composition of claim 1 wherein the amount of acid or salt is in the range of approximately 0.15 to 0.50 parts by weight per 100 parts by weight of magnesium hydroxide. The composition of claim 1 wherein the anhydride grafted polyethylene comprises approximately 0.05 to 5 parts by weight of anhydride per 100 parts by weight of polyethylene. (a) polyethylene grafted with maleic anhydride in an amount of 0.1 to 2 parts by weight of maleic anhydride per 100 parts by weight of polyethylene having a density within the range of 0.860 to 0.915 g / cm 3; And (b) in an amount of approximately 100 to 180 parts by weight per 100 parts by weight of anhydride grafted polyethylene, wherein the magnesium hydroxide is less than 3.0 × 10 ⁻³ in the direction of (1) (101), (2 Has a crystal size of 800 angstroms or more in the (101) direction and a surface area of 10 m ² / g or less determined by the (3) BET method, and approximately 8 to 24 carbons in an amount of about 0.15 to 0.5 parts by weight per 100 parts by weight. And magnesium hydroxide having a surface treated with an unsaturated carboxylic acid having atoms. A wire or cable comprising an electrical conductor or transmission medium surrounded by one or more collisions of the composition as defined in claim 1.